Abstract
Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M 23 C 6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.
Original language | English |
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Title of host publication | Minerals, Metals and Materials Series |
Publisher | Springer International Publishing |
Pages | 1859-1868 |
Number of pages | 10 |
ISBN (Print) | 9783030046385, 9783030046392, 9783319515403, 9783319651354, 9783319728520, 9783319950211 |
DOIs | |
State | Published - 2019 |
Externally published | Yes |
Event | 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019 - Boston, United States Duration: Aug 18 2019 → Aug 22 2019 |
Publication series
Name | Minerals, Metals and Materials Series |
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ISSN (Print) | 2367-1181 |
ISSN (Electronic) | 2367-1696 |
Conference
Conference | 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019 |
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Country/Territory | United States |
City | Boston |
Period | 08/18/19 → 08/22/19 |
Funding
This research was sponsored by U.S. Department of Energy/Office of Nuclear Energy through Light Water Reactor Sustainability R&D Program and International Nuclear Energy Research Initiative (I-NERI) Program. Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract No. DEAC05-76RL01830. APT and FIB/SEM were performed at PNNL’s Environmental Molecular Sciences Laboratory, a Department of Energy—Office of Biological & Environmental Research national scientific user facility.
Keywords
- Duplex stainless steel
- G-phase precipitation
- Solute segregation
- Spinodal decomposition
- Thermal aging degradation